1. Field of the Invention
This invention relates to apparatus and methods for automatically loading on a pallet a random set of different size and weight boxes. More particularly, this invention relates to automated palletizing without a prior knowledge of the boxes to be loaded.
2. Description of the Prior Art
Manual loading of boxes, or shipping cartons, onto a pallet entails high labor costs and high possibility of injuries. In addition, it is difficult to load a random set of different size and weight boxes so the resulting pallet is stable.
Early attempts at palletizing boxes automatically could only handle boxes which were all the same size. Henderson U.S. Pat. No. 4,786,229 is an example of this sort of system.
More recently, attempts have been made to load unequal size and weight boxes by automated palletizing. These inventions fall into two categories. The first type utilizes an operator who has knowledge of the size and weight of all of the boxes to be loaded. The operator designates to a computer the location of each box on the pallet, for example with the aid of a graphic terminal. The computer then determines the optimum loading sequence, and a marshalling device puts the boxes in that order. The boxes are then loaded on the pallet by a robot arm controlled by the computer. Examples include Konishi et al. U.S. Pat. No. 4,641,271, Tenma et al. U.S. Pat. No. 4,692,876, and Roccabianca et al. U.S. Pat. No. 4,746,255. These inventions require a prior knowledge of all of the boxes to be palletized. Also, an operator must still determine the pallet configuration. Thus, the process is slow, and the configuration is optimized for stability only to the extent permitted by human error.
In the last few years, work has been done on a second type of palletizing device, which uses an expert system to determine the pallet configuration. See, for example, "An Expert System Approach to Palletizing Unequal-sized Containers," Gilmore et al., SPIE Application of Artificial Intelligence, March 1989, and "Palletizing Unequal-Sized Containers," Gilmore et al. Proceedings of SPIE, March 1989. Gilmore has modelled a system which can automatically determine pallet configuration for different sizes and weights of boxes without operator assistance if the system has a prior knowledge of the size and weight of every box in the entire pallet load.
The need remains in the art for an automated palletizing system that can operate "on the fly", continually remapping optimal loading configuration as the pallet is being loaded, and based on what remaining boxes randomly appear on the line to be loaded on the pallet.